Then of course, as mentioned above, the RMA on an S9 is pretty much a joke ... so you gotta hope your S9 never fails ...
One of my two S9s had one hash board stop working. After some research I found I could get it replaced for about $600.00 . At the time the S9 was selling for under $1200. Needless to say I have mined on with only 2/3rds of one of my S9s. I probably should buy a 1000 Watt power supply to power the 2/3rd S9 and free up its power supply for use with a 741/761/A8.